(491e) Ammonia-Based Electrified Processes Integrated with Fuel Cell

Liquid carriers will play a significant role in diversifying Europe energy supply corridor, transporting hydrogen at scale, across large distances. As a mass-produced, low cost, and carbon-free chemical, ammonia has proven itself as a sustainable candidate. It has been produced industrially for over 75 years, with a large well-established infrastructure already available. Ammonia can be directly used in fuel cells (FC) for electrical power production or can be decomposed to hydrogen for utilization in hydrogen fuel-cells. Both solutions present some bottlenecks. Direct ammonia fuel cells still suffer from difficulties in identifying good anodic and cathodic electrocatalysts, ammonia crossover through membranes, oxidation of ammonia to NO, long-term stability, or long start-up time for solid-oxide fuel cells. On the other hand, ammonia decomposition to hydrogen is endothermal, requiring high thermal energy, which is traditionally provided by external combustion; state-of-art ammonia crackers operate at temperature of about 850 – 950 °C, adopting nickel supported on aluminum oxide based catalyst. Ammonia cracking can be followed by hydrogen separation for utilization in fuel cell. In fuel cell integrated systems, dissipated heat and some of the produced electric power can be also used for ammonia cracking purposes, realizing self-sustained auto-thermal processes. This can significantly reduce costs of thermal energy, materials, and drastically abate emissions. However the best process configuration for integrated systems is not trivial and is strictly dependent on the type of adopted fuel cell, the overall balance of plant, and the technological solutions proposed in the cracking/separation systems.

On this basis, in this work we carry out a comparative energetic assessment of different technological solutions for the described integrated systems, screening the available state-of-art component performances, allowing to choose the most energetically optimized technological solutions. Different configurations adopting low-temperature and high-temperature PEM fuel cell, and direct ammonia solide oxide fuel cell, are evaluated and compared with respect to the possible heat recovery, the overall energetic efficiency, and the relevant emissions.